tofu-output

tofu-output action

This is one of a suite of OpenTofu related actions - find them at dflook/terraform-github-actions.

Retrieve the root-level outputs from an OpenTofu configuration.

Inputs

• path

  Path to the OpenTofu root module

  • Type: string
  • Optional
  • Default: The action workspace

• workspace

  OpenTofu workspace to get outputs from

  • Type: string
  • Optional
  • Default: default

• backend_config

  List of OpenTofu backend config values, one per line.

  with:
    backend_config: token=${{ secrets.BACKEND_TOKEN }}

  • Type: string
  • Optional

• backend_config_file

  List of OpenTofu backend config files to use, one per line. Paths should be relative to the GitHub Actions workspace

  with:
    backend_config_file: prod.backend.tfvars

  • Type: string
  • Optional

Environment Variables

• TERRAFORM_CLOUD_TOKENS

  API tokens for cloud hosts, of the form <host>=<token>. Multiple tokens may be specified, one per line. These tokens may be used with the remote backend and for fetching required modules from the registry.

  e.g:

  env:
    TERRAFORM_CLOUD_TOKENS: app.terraform.io=${{ secrets.TF_CLOUD_TOKEN }}

  With other registries:

  env:
    TERRAFORM_CLOUD_TOKENS: |
      app.terraform.io=${{ secrets.TF_CLOUD_TOKEN }}
      tofu.example.com=${{ secrets.TF_REGISTRY_TOKEN }}

  • Type: string
  • Optional

• TERRAFORM_SSH_KEY

  A SSH private key that OpenTofu will use to fetch git module sources.

  This should be in PEM format.

  For example:

  env:
    TERRAFORM_SSH_KEY: ${{ secrets.TERRAFORM_SSH_KEY }}

  • Type: string
  • Optional

• TERRAFORM_PRE_RUN

  A set of commands that will be ran prior to tofu init. This can be used to customise the environment before running OpenTofu.

  The runtime environment for these actions is subject to change in minor version releases. If using this environment variable, specify the minor version of the action to use.

  The runtime image is currently based on debian:bullseye, with the command run using bash -xeo pipefail.

  For example:

  env:
    TERRAFORM_PRE_RUN: |
      # Install latest Azure CLI
      curl -skL https://aka.ms/InstallAzureCLIDeb | bash
      
      # Install postgres client
      apt-get install -y --no-install-recommends postgresql-client

  • Type: string
  • Optional

• TERRAFORM_HTTP_CREDENTIALS

  Credentials that will be used for fetching modules sources with git::http://, git::https://, http:// & https:// schemes.

  Credentials have the format <host>=<username>:<password>. Multiple credentials may be specified, one per line.

  Each credential is evaluated in order, and the first matching credentials are used.

  Credentials that are used by git (git::http://, git::https://) allow a path after the hostname. Paths are ignored by http:// & https:// schemes. For git module sources, a credential matches if each mentioned path segment is an exact match.

  For example:

  env:
    TERRAFORM_PRE_RUN: |
      # Install latest Azure CLI
      curl -skL https://aka.ms/InstallAzureCLIDeb | bash
      
      # Install postgres client
      apt-get install -y --no-install-recommends postgresql-client
    TERRAFORM_HTTP_CREDENTIALS: |
      example.com=dflook:${{ secrets.HTTPS_PASSWORD }}
      github.com/dflook/terraform-github-actions.git=dflook-actions:${{ secrets.ACTIONS_PAT }}
      github.com/dflook=dflook:${{ secrets.DFLOOK_PAT }}
      github.com=graham:${{ secrets.GITHUB_PAT }}  

  • Type: string
  • Optional

Outputs

An action output will be created for each output of the OpenTofu configuration.

For example, with the OpenTofu config:

output "service_hostname" {
  value = "example.com"
}

Running this action will produce a service_hostname output with the value example.com.

Primitive types (string, number, bool)

The values for these types get cast to a string with boolean values being 'true' and 'false'.

Complex types (list/set/tuple & map/object)

The values for complex types are output as a JSON string. OpenTofu list, set & tuple types are cast to a JSON array, map and object types are cast to a JSON object.

These values can be used in a workflow expression by using the fromJSON function

Example usage

String

This example uses an OpenTofu string output to get a hostname:

on: [push]

jobs:
  show_hostname:
    runs-on: ubuntu-latest
    name: Show the hostname
    steps:
      - name: Checkout
        uses: actions/checkout@v3

      - name: Get outputs
        uses: dflook/tofu-output@v1
        id: tf-outputs
        with:
          path: my-terraform-config

      - name: Print the hostname
        run: echo "The hostname is ${{ steps.tf-outputs.outputs.hostname }}"

Complex output

This example gets information from object and array(object) outputs.

With this OpenTofu config:

output "vpc" {
  value = aws_vpc.test
}
output "subnets" {
  value = [aws_subnet.a, aws_subnet.b, aws_subnet.c]
}

We can use the workflow:

jobs:
  output_example:
    runs-on: ubuntu-latest
    name: An example of workflow expressions with tofu output
    steps:
      - name: Checkout
        uses: actions/checkout@v3

      - name: Get outputs
        uses: dflook/tofu-output@v1
        id: tf-outputs
        with:
          path: my-terraform-config

      - name: Print VPC
        run: |
          echo "The vpc-id is ${{ fromJson(steps.tf-outputs.outputs.vpc).id }}"
          echo "The subnet-ids are ${{ join(fromJson(steps.tf-outputs.outputs.subnets).*.id) }}"          

Which will print to the workflow log:

The vpc-id is vpc-01463b6b84e1454ce
The subnet-ids are subnet-053008016a2c1768c,subnet-07d4ce437c43eba2f,subnet-0a5f8c3a20023b8c0